Light beam delivery system with power, wavelength and spot size control

Abstract

A beam delivery system for treating target tissue that includes an input for receiving a light beam, a variable attenuator for providing variable attenuation of the light beam, a power and wavelength detection assembly, a spot size adjustment assembly, and a controller. The power and wavelength detection assembly measures the power level of the beam, and detects when unwanted wavelengths are present in the light beam. The spot size adjustment assembly selectively feeds the beam through different optical fibers to achieve different spot sizes of the beam. The controller controls the variable attenuator, the power and wavelength detection assembly, and the spot size adjustment assembly to achieve the desired power and wavelength, and beam spot size.

1. A beam delivery system for treating target tissue comprising:
 an input for receiving a light beam; 
 a plurality of optical elements for delivering the light beam from the input to target tissue; 
 one or more pick-off optical elements for directing a first portion of the light beam to a first power detector for measuring a power level of the light beam first portion and for directing a second portion of the light beam to a second power detector for measuring a power level of the light beam second portion; 
 a first filter positioned to filter out or diffract certain wavelengths of light from the light beam first portion before reaching the first detector; and 
 a controller for determining any difference between the power levels measured by the first and second detectors, and for taking a predetermined action if the determined difference exceeds a predetermined value. 
 
     
     
       2. The beam delivery system of  claim 1 , wherein the input is an output end of an optical fiber. 
     
     
       3. The beam delivery system of  claim 1 , wherein the one or more pick-off optical elements comprise:
 a first beam splitter disposed in the light beam for extracting the first portion from the light beam by reflection; and 
 a second beam splitter disposed in the light beam for extracting the second portion from the light beam by reflection. 
 
     
     
       4. The beam delivery system of  claim 1 , further comprising:
 a second filter positioned to filter the light beam second portion before reaching the second detector, wherein the second filter has different wavelength filtering characteristics from that of the first filter. 
 
     
     
       5. The beam delivery system of  claim 1 , further comprising:
 a first aperture plate defining a first aperture aligned to the light beam first portion; 
 a first diffuser aligned to the light beam first portion; 
 a second aperture plate defining a second aperture aligned to the light beam first portion; and 
 a second diffuser aligned to the light beam second portion. 
 
     
     
       6. The beam delivery system of  claim 1 , further comprising:
 a variable attenuator disposed in the light beam before the light beam reaches the one or more pick-off optical elements. 
 
     
     
       7. The beam delivery system of  claim 1 , wherein the first filter comprises different portions thereof with differing wavelength filtering characteristics, and wherein the controller is configured to selectively place the different portions of the first filter in the light beam first portion. 
     
     
       8. The beam delivery system of  claim 1 , wherein the first filter attenuates the certain wavelengths from the first light beam. 
     
     
       9. The beam delivery system of  claim 1 , wherein the first filter diffracts the certain wavelengths from the first light beam. 
     
     
       10. The beam delivery system of  claim 1 , wherein the predetermined action is an indication of a fault condition. 
     
     
       11. A beam delivery system, comprising:
 an input for receiving a light beam; 
 a variable attenuator for providing variable attenuation of the light beam; 
 a power and wavelength detection assembly, comprising:
 one or more pick-off optical elements for directing a first portion of the light beam to a first power detector for measuring a power level of the light beam first portion, and for directing a second portion of the light beam to a second power detector for measuring a power level of the light beam second portion, 
 a first filter positioned to filter out or refract certain wavelengths of light from the light beam first portion before reaching the first detector; 
 a spot size adjustment assembly, comprising: 
 a first scanning optical element for moving a direction of propagation of the light beam in a first direction and between a first position where the light beam impinges on a beam dump and a second position where the light beam is aligned to and passes through an aperture, 
 a second scanning optical element for selectively moving a direction of propagation of the light beam in a second direction between a plurality of positions, wherein the beam dump and the aperture are disposed between the first and second scanning optical elements, 
 a plurality of optical fibers each having their input ends disposed at one of the plurality of positions for selectively receiving the light beam, and 
 a plurality of lenses disposed at output ends of the plurality of optical fibers for collimating the light beam exiting the output ends, wherein the plurality of optical fibers and the plurality of lenses are configured to produce different spot sizes of the light beam; and 
 
 a controller for controlling the variable attenuator, the power and wavelength detection assembly, and the spot size adjustment assembly, wherein the controller is configured to:
 determine a power level of the light beam using the power detectors, and adjust the variable attenuator in response to the determined power level, 
 determine any difference between the power levels measured by the first and second detectors, and take a predetermined action if the determined difference exceeds a predetermined value, 
 control the first scanning optical element to direct the light beam to the beam dump in a standby mode and through the aperture in a non-standby mode, and 
 control the second scanning optical element to direct the light beam to the input end of one of the optical fibers associated with a desired spot size. 
 
 
     
     
       12. The beam delivery system of  claim 11 , wherein the one or more pick-off optical elements comprise:
 a first beam splitter disposed in the light beam for extracting the first portion from the light beam by reflection; and 
 a second beam splitter disposed in the light beam for extracting the second portion from the light beam by reflection. 
 
     
     
       13. The beam delivery system of  claim 11 , further comprising:
 a second filter positioned to filter or diffract the light beam second portion before reaching the second detector, wherein the second filter has different wavelength filtering characteristics from that of the first filter. 
 
     
     
       14. The beam delivery system of  claim 11 , wherein the first filter comprises different portions thereof with differing wavelength filtering characteristics, and wherein the controller is configured to selectively place the different portions of the first filter in the light beam first portion. 
     
     
       15. The beam delivery system of  claim 11 , further comprising:
 a first aperture plate defining a first aperture aligned to the light beam first portion; 
 a first diffuser aligned to the light beam first portion; 
 a second aperture plate defining a second aperture aligned to the light beam first portion; and 
 a second diffuser aligned to the light beam second portion. 
 
     
     
       16. The beam delivery system of  claim 11 , wherein the beam dump and the aperture are integrally formed as a single device. 
     
     
       17. The beam delivery system of  claim 11 , wherein the first direction is orthogonal to the second direction. 
     
     
       18. The beam delivery system of  claim 11 , wherein the plurality of positions are disposed along a single line. 
     
     
       19. The beam delivery system of  claim 11 , wherein the single line extends parallel to the second direction. 
     
     
       20. The beam delivery system of  claim 11 , wherein the predetermined action is an indication of a fault condition.